Pitcher type water purifier and purification cartridge for the water purifier

ABSTRACT

In a combination including a pitcher-type water purifier and its purification cartridge, which can adsorb and eliminate chemical substances such as chlorine from raw water, eliminate bacteria, and prevent propagation of bacteria and provide safe purified water in a short period of time, even when the purified water has been stored for a long-period time, the pitcher type water purifier contains a casing divided into upper and lower parts as a raw water reservoir portion and a purified water reservoir portion, and has a purified water pouring opening in the purified water reservoir portion; and the purification cartridge has a raw water inlet in an upper face thereof and a purified water outlet in a bottom face, and adsorbent is filled in an upper layer of an interior thereof and hollow fiber membranes are filled in a lower layer thereof at an opening rate σ of 25-58%.

CROSS-REFERENCED APPLICATIONS

This application is the National phase of International ApplicationPCT/JP01/11087, the complete disclosure of which is incorporated hereinby reference, filed 18 Dec. 2001, which designated the U.S. and thatInternational Application was not published under PCT Article 21(2) inEnglish.

TECHNICAL FIELD

The present invention relates to a pitcher type water purifier thatenables purifying a relatively large amount of raw water at one time anda casing of that is formed with a purified water pouring opening, and areplaceable purification cartridge that is used with the water purifier.

BACKGROUND ART

Various kinds of pitcher type water purifiers have hitherto beenproposed which can purify a relatively large amount of raw water ofapproximately 1 to 2 liters at one time, which can be kept in custodyin, for example, a refrigerator, and which is formed with a pouringopening from which water is poured into a cup.

For example, a pitcher type water purifier that is disclosed in JapanesePatent Application Laid-Open No. H-11-319799 is constructed in the waythe water purifier has a casing having a pouring opening and a handleand the interior thereof is partitioned into upper and lower parts, as araw water reservoir portion and a purified water reservoir portion, witha partition wall, a part of that has openings, being interposed betweenthe both portions. And, on the bottom portion of the raw water reservoirportion, a circular-columnar purification cartridge is disposed in theway of being replaceable and in a state where the cartridge as a wholeis kept projecting into the purified water reservoir portion. Thepurification cartridge has a raw water inlet shaped like a mesh at itsupper part and has a purified water outlet shaped like a mesh at itsbottom part, and activated carbon and/or ion-exchange resin are filledin its interior as adsorbent. In some cases, in place of ordinaryactivated carbon, antibacterial activated carbon is filled.

In the above-described pitcher type water purifier, the raw water thathas been supplied into the raw water reservoir portion at the upper partof the casing is passed through the purification cartridge under a waterpressure that corresponds to its own weight. At this time, through theaction of adsorbent such as activated carbon, ion-exchange resin, andthe like, organic substances such as residual chlorine, chlorinatedodor, mold odor, and trihalomethane, and impurities such as heavy metalor aluminum, which are contained in the raw water, are eliminated,whereby the water is purified. Thereafter, the water is stored into thepurified water reservoir located at the lower part.

However, as the conventional pitcher type water purifiers, there is onlya type wherein adsorbent such as activated carbon or ion-exchange resinfilled in the purification cartridge eliminates, due to the action ofadsorption, etc., the chemical substances in the raw water. Further, inthe purification cartridge, for the purpose of preventing such adsorbentfrom flowing out into the outside thereof, a main body thereof isconstructed in the form of a mesh and in addition a filtering materialwith coarse mesh such as non-woven fabric is disposed therein. For thatreason, conversely, bacteria or microbes are likely to propagatethemselves. The conventional water purifier could not eliminatesubstances even up to such very fine substances.

Ordinarily, in the water of the public water line, in order to preventthe bacteria contamination, there is added thereto chemicals such aschlorine, as disinfectant that has strong sterilizing effect, less harmto the human body, and a high residual effect. Thereby, that water ismanaged. However, it is the point in time when it has been just suppliedfrom the tap. In contrast to this, in the case of a pitcher type waterpurifier, according to the use thereof, there is also a case where it isstored in a refrigerator for a long period of time such as one week orso. Therefore, although it is stored as low-temperature storage, in acase where residual chlorine is eliminated by adsorbent such asactivated carbon and as a result a minute amount of bacteria or microbesexist in the water having had the sterilizing effect lost, the followingpossibility exists. Namely, during such storage, such bacteria ormicrobes will propagate themselves and, in some cases, they will havepropagated themselves up to the concentration that has effect upon thehuman body.

In order to eliminate those bacteria or microbes as well, as in the caseof, for example, a cup-type portable water purifier disclosed inJapanese Utility Model Application Laid-Open No. H-5-15993 or anordinary directly-connected-to-tap type water purifier, filling a hollowfiber membrane within a purification cartridge and thereby filteringsuch bacteria or microbes through the use of that hollow fiber membraneare effective.

By the way, in the hollow fiber membrane, in terms of its structure, ina case where the water pressure is low, the water passage rate is verylow. Therefore, conventionally, as in the case of the cup-type waterpurifier disclosed in the said Japanese Utility Model ApplicationLaid-Open No. H-5-15993, the use of it was limited to the cases wherethe amount of water that is to be purified at one time was small and,also, as in the case of the directly-connected-to-tap water purifier,the use of it was limited to the case where the water pressure from thetap was utilized.

However, the pitcher type water purifier purifies such a relativelylarge amount of water as to an extent of 1 to 2 liters or so, or atleast 500 milliliters or so. In addition, the pressure of that water isonly the weight alone of the raw water, itself, that is stored in theraw water reservoir portion that is located at the upper part. For thatreason, in the case of having filled the hollow fiber membrane intowithin the purification cartridge of the above-described pitcher typewater purifier, the time for processing the water becomes very long. Inthe case of the pitcher type water purifier in which using itimmediately after supply of the water is also taken into account, thedemerit that a long time is needed for purification processing is a veryserious problem.

The present invention has been achieved in order to solve theabove-described problems and has an object to provide a pitcher typewater purifier and a purification cartridge for use therewith, which canpurify a relatively large amount of raw water, that is to an extent ofat least 500 milliliters or so, in a short period of time, whichpurifier and cartridge not only adsorb and eliminate organic substancessuch as residual chlorine, chlorinated odor, mold odor andtrihalomethane, and impurities such as heavy metal and aluminum, butalso 0.1 μm or more of very fine particles including bacteria ormicrobes and, even when storing the purified water for a long period oftime, can prevent bacteria or microbes from propagating themselves andtherefore can ensure a purification performance of high safety in termsof sanitation.

DISCLOSURE OF THE INVENTION

To achieve the above object, a first aspect of the invention provides apitcher type water purifier comprising a casing that is divided intoupper and lower parts, as a raw water reservoir portion and a purifiedwater reservoir portion, the casing having a purified water pouringopening that is communicated with the purified water reservoir portion;and a purification cartridge replaceably disposed between the raw waterreservoir portion and the purified water reservoir portion and having araw water inlet open to the raw water reservoir portion and a purifiedwater outlet open to the purified water reservoir portion, characterizedin that adsorbent is filled in an upper layer of the interiorcommunicated with the raw water inlet and hollow fiber membranes arefilled in a lower layer thereof; and the opening rate σ of the hollowfiber membranes is 25-58%.

Incidentally, assuming that S represents the cross-sectional area of thespace of filling of the hollow fiber membranes in the purificationcartridge; A represents the cross-sectional area of the outside diameterof a single hollow fiber membrane; and F represents the number ofopenings of the hollow fiber membranes, the opening rate σ of the hollowfiber membranes can be determined using the following equation.σ(%)={(A×F)/S}×100

In this water purifier, first, raw water is supplied to the raw waterreservoir portion. This raw water, due to its own weight, is introducedfrom the raw water inlet of the purification cartridge into thepurification cartridge and, first, is contacted with adsorbent filled inthe upper layer of the interior. Through the action of this adsorbent,organic substances such as residual chlorine, chlorinated odor, moldodor and trihalomethane, and impurities such as heavy metal and aluminumare adsorbed and eliminated.

As adsorbent, there are a powdered adsorbent, a granulate adsorbentprepared by granulating the powdered adsorbent, a fibrous adsorbent,etc. As such adsorbents, there are known adsorbents that includeinorganic adsorbents such as natural material adsorbents (naturalzeolite, silver zeolite, acidic china clay, etc.), and syntheticmaterial adsorbents (synthetic zeolite, bacteria-adsorbing polymer,phosphor ore, molecular sieve, silica gel, silica alumina gel-basedadsorbent, porous glass, etc.), organic adsorbents such as powderedactivated carbon, granule activated carbon, fibrous activated carbon,block-like activated carbon, extrusion-molded activated carbon, formedactivated carbon, molecule-adsorbing resin, synthetic material-basedgranule activated carbon, synthetic material-based fiber-like activatedcarbon, ion-exchange resin, ion-exchange fiber, chelate resin, chelatefiber, high-absorption resin, high water-absorption resin,oil-absorption resin, oil-absorbing agent, etc. Above all, activatedcarbon, which has excellent adsorbing effect for residual chlorine,organic compounds such as mold odor and trihalomethane in raw water, issuitably used. Among activated carbons, fiber-like activated carbon issuitably used because the area of contact with the liquid to be filteredis large and the adsorbing effect and water-passing capability aregreat.

As the activated carbon, there are, for example, plant-matter (wood,cellulose, sawdust, charcoal, coconut palm shell charcoal, non-processedraw ash, etc.), coal-matter (peat, lignite, brown coal, bituminous coal,barley coal, tar, etc.), petroleum-matter activated carbon (petroleumleavings, sulfuric acid sludge, oil carbon, etc.), pulp spent liquor,synthetic resin, etc., which are carbonized, and, according to thenecessity, subjected to gas activation (water vapor, carbon dioxide,air, etc.) or to chemical activation (calcium chloride, magnesiumchloride, zinc chloride, phosphoric acid, sulfuric acid, caustic soda,KOH, etc.). As the fibrous activated carbon, there are, for example,substances which is carbonized and activated from precursor such aspolyacrylonytril (PAN), cellulose, phenol, petroleum pitch.

As the activated carbon, there can be used powdered activated carbon,granular activated carbon granulated from this powdered activatedcarbon, granular activated carbon, fibrous activated carbon, formedactivated carbon obtained by coagulating powdered and/or granularactivated carbon by the use of binder. Among these, granular activatedcarbon is suitably used from the standpoint of its handleability and thecost. As the activated carbon, one having a filling density of 0.1-0.5g/ml, an adsorbed amount of iodine of 800-4000 mg/g, and a granule sizeof 0.075-6.3 mm as its description is preferable. Further, in a casewhere silver is adhered to and/or mixed with the activated carbon, itcan suppress the propagation of bacteria and microbes.

Next, by the hollow fiber membranes filled in the lower layer of thecartridge interior, granules, including microbes and bacteria, whosesize is 0.1 μm or more, are filtered and eliminated. As the hollow fibermembranes, there can be used various kinds of porous and tubular hollowfiber membranes. There can be used ones comprised of various kinds ofmaterials which are based on the use of, for example, cellulose,polyolefin (polyethylene, polypropylene), polyvinyl alcohol,ethylene/vinyl alcohol copolymer, polyether, polymethacrylic acid methyl(PMMA), polysulfone, polyacrylonitrile, polytetrafluoroethylene(Teflon), polycarbonate, polyester, polyamide, aromatic polyamide, etc.Among these, taking into account the handleability and processability ofthe hollow fiber membranes and in addition thermal disposability at thetime of disposal, etc., the hollow fiber membranes based on the use ofpolyolefin such as polyethylene and polypropylene are preferable.

Also, although not particularly limited, preferably, the outsidediameter of the hollow fiber membrane is 20-2000 μm, the pore diameterthereof is 0.01-1 μm, the porosity thereof is 20-90%, and the hollowfiber membrane thickness thereof is 5-300 μm.

Also, the hollow fiber membrane, preferably, is the so-called“permanently made-hydrophilic hollow fiber membrane” the surface of thathaving hydrophilic groups. When the surface of the hollow fiber membranehas hydrophobic nature, it becomes very difficult to filter and passwater with the water pressure that corresponds to the weight of thesupplied water itself.

Furthermore, in some cases, air bubbles contained in the supplied waterkeep dwelling at the surface of the hollow fiber membrane to therebyobstruct the filtering and passing of the water therethrough and also todecrease the filtering flow rate. In such a case, the purificationcartridge may be made to be one in which the hydrophobic hollow fibermembrane and the hydrophilic hollow fiber membrane co-exist, to therebymake it easy to eliminate such air bubbles.

The purified water that has been thus obtained is guided from thepurified water outlet of the purification cartridge into the purifiedwater reservoir portion, and is stored within the purified waterreservoir portion. And, when necessary, the purified water istransferred from the pouring opening of the pitcher to a cup, etc.

In the above-described pitcher type water purifier, the opening rate σof the hollow fiber membrane can be set to be 25-58%. Thereby, the waterpassage rate of the raw water in the purification cartridge can beincreased up to around a value that makes the pitcher type waterpurifier usable as it. Thereby, a relatively large amount of raw watercan be purified in a short period of time. In addition, by filtrationusing the hollow fiber membranes, even bacteria or microbes that areunable to be eliminated with the use of adsorbent such as activatedcarbon and ion-exchange resin are able to be eliminated. And, even in acase where the water that has had chemicals such as chlorine etc.,eliminated therefrom and that has thus been purified has been stored fora long period of time, bacteria or microbes will not propagatethemselves. Therefore, purified water with high safety can be preservedfor a long period of time and, from the standpoint of sanitation aswell, this pitcher type water purifier is extremely excellent. Further,by using a resin having antibacterial agent added thereto as theconstruction material for the casing and the purification cartridge,even greater effect in terms of sanitation can be achieved.

Incidentally, it is preferable that the opening rate of the hollow fibermembranes be in a range of 30-55%, and, further, it is most preferablefrom the standpoint of increasing the water passage rate that theopening rate of the hollow fiber membranes is in a range of 35-52%.

Here, if filling a hollow fiber membrane knitted fabric, described inJapanese Utility Model Registration No. 1994065, into the case member ofthe purification cartridge, because of being able to easily know thenumber of the hollow fiber membranes used, it is easier to manage theopening rate. In addition, since the hollow fiber membrane knittedfabrics can be easily filled as a coiled-sushi configuration or foldedconfiguration, it is easy to manage the distances between the hollowfiber membrane knitted fabrics so that such distances may be equal.Also, the hollow fiber membranes can also be easily and evenly dispersedeven if the opening rate is varied. Further, even after the hollow fibermembranes have been processed as the purification cartridge, ifloosening the warp yarns in the vicinity of the end portions of one ormore hollow fiber membranes that have been used as the weft yarns of thehollow fiber membrane knitted fabric, one or more hollow fiber membranespreferably become more dispersed.

A second aspect of the invention is characterized in that the casingcomprises pressurizing means with respect to the raw water reservoirportion.

By the casing comprising the pressurizing means with respect to the rawwater reservoir portion in this way, the raw water within the raw waterreservoir portion can positively be introduced into the purificationcartridge by such pressure as air pressure, with the result that theprocessing speed is remarkably increased.

As the above-described pressurizing means, for example, the invention ina third aspect is characterized by the pressurizing means comprising apressurizing pump. Or, in a fourth aspect, the invention ischaracterized in that the pressurizing means comprises a compressionspring. As each of these pressurizing means, it is possible to use aconventionally known structure.

A fifth aspect of the invention is the purification cartridge for thepitcher type water purifier that is replaceably disposed between the rawwater reservoir portion and the purified water reservoir portion, whichare the separated upper and lower parts inside the casing which has apurified-water pouring opening. This purification cartridge ischaracterized in that it has a raw water inlet which is open to the rawwater reservoir portion and a purified water outlet which is open to thepurified water reservoir portion, and that adsorbent is filled in anupper layer of the interior communicated with the raw water inlet and ahollow fiber membrane is filled in a lower layer thereof; and theopening rate σ of hollow fiber membranes is 25-58%.

In the above-described purification cartridge for the pitcher type waterpurifier, by making the opening rate of hollow fiber membranes 25-58%,it is possible to ensure the water passage rate that substantiallyenables the pitcher type water purifier to be used as it. Incidentally,the structure thereof is a simple one in which adsorbent is filled inthe upper layer of the interior communicated with the raw water inletand hollow fiber membranes are filled in the lower part of thatinterior. And the manufacturing cost is also low. In addition, thecartridge is light in weight and the replacing operation is also easy.Moreover, by providing the lug portion in the upper part, the replacingoperation can be made easier.

As the purification cartridge, for example, a sixth aspect of theinvention is characterized in that the purification cartridge has acolumnar configuration; the upper layer thereof in which the adsorbentis filled has the raw water inlet; and the lower layer thereof in whichthe hollow fiber membrane is filled has the purified water outlet.

The above-described columnar purification cartridge can make the waterpassage channel elongate and therefore enables sufficiently ensuring thetime period for contact of the raw water with adsorbent. Besides, thatcartridge resembles the conventional purification cartridge for thedirectly-connected-to-tap water purifier in terms of the formation, andtherefore can have its design easily changed when manufactured.

Or, for example, a seventh aspect of the invention is characterized inthat the purification cartridge consists of a flat plate portion thathas a flat surface configuration substantially the same as the bottomsurface configuration of the raw water reservoir portion and a columnarportion that projects downward from the bottom surface of the flat plateportion; the flat plate portion is filled with adsorbent and thecolumnar portion is filled with the hollow fiber membrane; and the flatplate portion has the raw water inlet and the columnar portion has thepurified water outlet.

In the purification cartridge of the invention, adsorbent is filled inthe flat plate portion having the flat surface configurationsubstantially the same as the bottom surface configuration of the rawwater reservoir portion while the raw water inlet is formed on thesurface of that flat plate portion. As a result of this, raw water canbe contacted with the adsorbent highly efficiently. Also, the hollowfiber membranes are filled in the columnar portion projecting downwardfrom the flat plate portion and so the water passage rate of the hollowfiber membrane is lower than that of adsorbent. Therefore, the raw watercan be made to stay in the flat plate portion for a necessary period oftime, so that it is possible to sufficiently eliminate chlorine and thelike by means of the adsorbent.

Also, an eighth aspect of the invention is characterized in that thepurification cartridge consists of a thick plate body that has a flatsurface configuration substantially the same as the bottom surfaceconfiguration of the raw water reservoir portion; and the upper layerthereof in which adsorbent is filled has the raw water inlet and thelower layer thereof in which the hollow fiber membrane is filled has thepurified water outlet.

The purification cartridge consisting of the thick plate body that hasthe flat surface configuration substantially the same as the bottomsurface configuration of the raw water reservoir portion can define theraw water reservoir portion and the purified water reservoir portion bymeans of this cartridge. Therefore, it is sufficient that the casing ofthe pitcher type water purifier is formed with a flange portion on theinner-peripheral wall surface for installing the purification cartridge.Therefore, the structure of the casing is simplified. Also, since thepurification cartridge has no portion that projects into the purifiedwater reservoir portion, it is not immersed in the purified water keptstaying within the purified water reservoir portion. Therefore it ispreferable from the viewpoint of sanitation as well.

These purification cartridges for the pitcher type water purifier,according to a ninth aspect of the invention, are characterized in thatthe amount of the adsorbent filled is 10-200 g in case of activatedcarbon; and the total membrane area of the hollow fiber membranes is0.1-1.0 m².

When the filling amount of activated carbon and the total membrane areaof the hollow fiber membranes are respectively in the above-describedranges, the pitcher type water purifier can sufficiently have, whileensuring the required processing speed as a pitcher type water purifier,the performance of adsorbing and eliminating chlorine or trihalomethaneby means of the adsorbent and the performance of filtering andeliminating bacteria and microbes by means of the hollow fibermembranes.

Further, according to a tenth aspect of the invention, the purificationcartridge is characterized in that it is dividable into the upper layerin which the adsorbent is filled and the lower layer in which the hollowfiber membrane is filled.

According to the raw water used, the service lives of the adsorbent andthe hollow fiber membrane may remarkably differ. In such a case, eitherone of them can be replaced or reproduced to, thereby waste is avoided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pitcher type water purifier accordingto a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view of the pitcher type waterpurifier.

FIGS. 3A and 3B are graphs each illustrating the correlation between anopening rate of a hollow fiber membrane and a filter performancethereof.

FIG. 4 is a sectional view of a pressurizing pump.

FIG. 5 is a sectional view of pressurizing means.

FIG. 6 is a longitudinal sectional view of a pitcher type water purifieraccording to a second embodiment of the present invention.

FIG. 7 is a longitudinal sectional view of a pitcher type water purifieraccording to a third embodiment of the present invention, and

FIG. 8 is a longitudinal sectional view of a purification cartridgeaccording to a fourth embodiment of the present invention.

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an explanation will be given of preferred embodiments ofthe present invention, concretely, with reference to the drawings.

As illustrated in FIGS. 1 and 2, according to a first embodiment of thepresent invention, a pitcher type water purifier 1 is constructed of acasing 10 and a purification cartridge 20. The casing 10 is constructedof a first main body portion 11 having a handle 11 a and a pouringopening 11 b, each of which has been formed integrally therewith, asecond main body portion 12 that is accommodated within a substantiallyupper-half portion of the casing main body, and a lid member 13 having alug portion 13 a formed at its center.

The first main body portion 11 consists of a transparent casing that hasa flat surface configuration, which is substantially trapezoidal. On aside wall surface corresponding to an shorter base of the trapezoid,there is formed the pouring opening 11 b that is inclined from around anintermediate portion of the height thereof toward an upper end edge. Onthe opposite side wall surface there is formed the handle 11 a.

A stepped portion 12 a is formed on an upper end edge of the second mainbody portion 12, and this stepped portion 12 a is placed upon, andengaged with, the edge of an upper end opening of the first main bodyportion 11. Thereby, it is accommodated within the first main bodyportion 11. The interior of this second main body portion 12 constitutesa raw water reservoir portion 1 a while a lower half portion of thefirst main body portion 11 constitutes a purified-water reservoirportion 1 b.

To the second main body portion 12, at a position corresponding to thepouring opening 11 b of the first main body portion 11, there ishinge-connected a substantially triangular lid piece 12 b that is forclosing the pouring opening 11 b. Further, in the central part of abottom wall portion of the second main body portion 12 there is formed acircular opening stepped portion 12 c. From this opening stepped portion12 c, a cup portion 12 d is formed in the way projecting downwardly. Abottom portion of this cup portion 12 d has only formed thereat forreinforcement a substantially cross-shaped beam member, whereby mostpart of it is open. It is to be noted that the cup portion 12 d is onlyformed for the purpose of ensuring the strength of the second main bodyportion 12. Therefore, when the strength of the second main body portion12 is ensured, the cup portion 12 d may be abated and it is sufficientthat the circular opening stepped portion 12 c be only formed.

In the cup portion 12 d of the second main body portion 12 there isaccommodated the substantially circular-columnar purification cartridge20 in a state where a flange portion 21 a formed on an upper end edgethereof is being fitted in the opening stepped portion 12 c. It is alsopossible to adopt a seal structure wherein a groove portion, into whichan O-ring or a gasket or the like is fitted, is formed in either one ofthe flange portion 21 a of the purification cartridge 20 and the openingstepped portion 12 c of the second main body portion 12, both of whichare closely fitted together through the use of such an O-ring, gasket,etc.

The purification cartridge 20 comprises a case member 21 the upper endof that is closed and that is substantially circular hollow cylindrical.With respect to the closed upper end portion there are formed a lugportion 22 and raw water inlets 23. On the other hand, the lower end ofthe case member 21, as a whole, is open and constitutes a purified wateroutlet 24. Right beneath the raw water inlets 23, at the position atwhich the flange portion 21 a is formed, there is located a filter 25consisting of a non-woven fabric. Further, at a substantially centralposition, as well, of the interior of the purification cartridge 20there is disposed a filter 25 consisting of a non-woven fabric, wherebythe interior of the case member 21 is partitioned into an upper part anda lower part. Adsorbent 26 is filled in the upper half part of theinterior of the case member 21. In the lower half part thereof a hollowfiber membrane module 27 is fitted in a state where the end portion ofthe openings of the hollow fiber membrane 27 b fixed using a pottingmaterial 27 a is in coincidence with the purified water outlets 24.

For example, as the hollow fiber membrane 27 b of the purificationcartridge 20, there is used the one that has an outside diameter of 380μm, an inside diameter of 270 μm, and a membrane thickness of 55 μm andthat is made of polyethylene capable of eliminating 90% or more ofparticles having a divided size of 0.2 μm. Within the interior of thecircular-columnar case member whose outside diameter is 54 mm, over thelength of approximately 60 mm as measured from the upper end, theadsorbent is filled and, over the length of approximately 50 mm asmeasured from the lower end, the hollow fiber membrane is filled.

Graphs in each of which there is plotted the relationship between theopening rate of the hollow fiber membrane 27 b and the filterperformance of it under the assumption that the membrane area of thehollow fiber membrane 27 b be fixed are illustrated in FIG. 3. Thegraphs of FIGS. 3A and 3B show the results that have been obtained byperforming filtering with the use of the pitcher type water purifieraccording to the first embodiment of the present invention, showing thetime period (minutes) required to filter 1L of water with its own weightand the flow rate of filtration (L/min./m²) per membrane area.

First, a pressure of 0.1 MPa was applied to only the purificationcartridge 20 as a single unit and, in this condition, water was passedthrough it, to thereby wet the hollow fiber membrane. Thereafter, waterwas filtered with its own weight. The filtration test was conducted oneach of the filling densities by the use of two purification cartridges.The black square point marks in the Figures are the plotting of eachresults.

The membrane area at each opening rate is as illustrated in Table 1below.

TABLE 1 Opening Rate (%) Membrane area (m²) 20.1 0.065 30.2 0.098 40.20.130 50.3 0.163 60.0 0.194

As apparent from FIG. 3A, in a case where the opening rate of the hollowfiber membrane 27 b is varied, as the opening rate increases, the timeperiod needed to filter 1L of water shortens. However, the extent towhich the filtering time period shortens decreases with an increase inthe opening rate. For example, in a case where the opening rate has beenincreased from 20% to 40%, the filtering time period shortens about 8minutes. However, even in a case where the opening rate has beenincreased from 40% to 60%, the shortened time period is only twominutes. Here, when this is converted to the flow rate of filtration perunit membrane area, it is seen that the flow rate decreases with anincrease in the opening rate, namely that as the opening rate increasesthe entire membrane ceases to be utilized uniformly.

In this way, unlike the water purifier which is used with the water linecapable of applying 0.1 MPa or more of pressure, in the pitcher typewater purifier which performs filtration with the use of the water's ownweight resulting from the head level of 5-30 cm or so, i.e. with the useof a very low pressure of 0.0005-0.003 MPa or so, the filter performanceis greatly affected by the opening rate of the membrane. Therefore theopening rate of the membrane should be strictly set.

In a case where the opening rate of the membrane is 60% or more, evenwhen increasing the membrane area, the filtering time period almost doesnot shorten. Therefore, the upper limit of the opening rate is preferredto be 58% or less. Also, in a case where the opening rate is less than25%, 15 minutes or more is needed to filter the water of 1 L, which isnot preferable. When the opening rate is within a range of 30-55%, thetime period that is needed to filter 1L of water is only to be fromabout 13 mins. to 9 mins. On the other hand, the flow rate of filtrationper unit membrane area does not greatly vary, either, and therefore themembrane is relatively uniformly utilized, which is preferable.Furthermore, it is most preferable, from the standpoint of makingcompatible the water passage rate and the membrane utilizationefficiency, that the opening rate be set to be 35-52%.

Also, in a case where using an activated carbon as adsorbent, it ispreferable that the filling amount of that activated carbon be set to be10-200 g; and the total membrane area of the hollow fiber membranes beset to be 0.1-1.0 m². Namely, preferably, the filling amount ofadsorbent and the total membrane area of the hollow fiber membrane aresuitably changed within such ranges according to the components, purposeand the performance of the raw water.

In the above-described pitcher type water purifier 1, supply of a rawwater into the interior (the raw water reservoir portion 1 a) of thesecond main body portion 12 permits the raw water to be introduced fromthe raw water inlets 23 of the purification cartridge 20, which has beenamounted on the bottom portion of the second main body portion 12, intothe interior of the purification cartridge 20. And, chlorine or chemicalsubstances such as trihalomethane are adsorbed and eliminated by theadsorbent 26. Thereafter, bacteria or microbes are further filtered bythe hollow fiber membrane 27 b, whereby the water is let out from thepurified water outlets 24 into the purified water reservoir portion 1 bof the first main body portion 11.

The speed, at this time, at which the raw water passes through thepurification cartridge 20 depends upon the water passage rate of thehollow fiber membrane 27 b. However, by making the opening rate of thehollow fiber membrane 27 b 30-55% as stated above, a sufficient waterpassage rate as a pitcher type water purifier is ensured.

In addition, the purified water that has been obtained using theabove-described purification cartridge 20 has no bacteria or microbes,which are completely filtered and eliminated therefrom by the hollowfiber membrane 27 b. Therefore, where having preserved the purifiedwater containing no chlorine therein for a long period of time, as well,there is no possibility that bacteria or microbes will propagatethemselves. Therefore, that purified water is excellent in terms ofsafety.

Incidentally, as stated above, by setting the opening rate of the hollowfiber membranes to be a value within the above-described range, thewater passage rate has been able to be enhanced up to a value enablingthe pitcher type water purifier to be used as itself. However, comparingto the use of the conventional purification cartridge having filledtherein only such an adsorbent as activated carbon and ion-exchangeresin, the water passage rate is low.

To increase the water passage rate, it is also considered to, forexample, dispose a packing on the peripheral edge of the lid member 13of the casing 10 to thereby enable the lid member 13 to be closelysealed to the second main body 12. Simultaneously, a pressurizing pump 2having formed therein a check valve 2 a such as that illustrated in FIG.4 is mounted to the lid member 13 to thereby forcedly feed the raw waterinto the purification cartridge 20. It is thereby possible to increasethe water passage rate of the purification cartridge 20 and therebyremarkably increase the purification processing rate.

Incidentally, as other conventional known pressurizing pumps, theirbasic structure is disclosed, for example, in Japanese Utility ModelApplication Laid-Open Nos. H4-118135, H6-39194, and H6-80684, etc.

Or, as illustrated in FIG. 5, the lid member 13 of the casing 10 isfixed to the upper end edge of the second main body portion 12 of thecasing 10 by means of, for example, screw engagement or the like.Further, a plate member 3 a the specific gravity of which is lighterthan that of the raw water W and the outer configuration of which is thesame as the inner-peripheral configuration of the second main bodyportion 12 is floated on the surface of the raw water W over an entireupper surface thereof. Between this plate member 3 a and the lid member13, a compression spring 3 b is disposed. By doing so, it is possible topress the raw water downward by means of the plate member 3 a andthereby positively feed the raw water into the purification cartridge.

Further, utilizing the fact that the water passage rate has decreased asa result of the use of the hollow fiber membrane 27 b in thepurification cartridge in comparison with the use of only adsorbentalone such as that consisting of activated carbon, ion-exchange resin,or the like, it is also possible to use such a purification cartridge 30as illustrated in FIG. 6.

Conventionally, for the purpose of ensuring a time for permitting theraw water to contact with adsorbent such as activated carbon orion-exchange resin and the like, for sufficiently adsorbing andeliminating chlorine or trihalomethane from the raw water by the use ofadsorbent such as activated carbon or ion-exchange resin and the like, apurification cartridge that is as stated above and that islongitudinally elongate circular-columnar was used and, thereby, thewater was passed from the upper end to the lower end thereof to ensure asufficient value of water passage distance. However, the above-describedcircular-columnar purification cartridge is caused to project into thepurified water reservoir 1 b and therefore is at all times immersed inthe purified water stored within that purified water reservoir 1 b. As amatter of course, the water is also kept entered into within thepurification cartridge immersed in the purified water. In view of this,in the case of, especially, the conventional water purifier in whichonly adsorbent alone is filled, such entry state is not preferable fromthe viewpoint of sanitation as well.

In contrast, in the purification cartridge using the hollow fibermembranes, the water passage rate of the hollow fiber membrane is lowerthan that of the adsorbent, therefore a sufficient time for contactbetween the raw water and the adsorbent can be ensured, with the resultthat it becomes possible to shorten the height dimension of the fillingportion of adsorbent.

According to a second embodiment of the present invention, asillustrated in FIG. 6, the purification cartridge 30 attached to a waterpurifier 1′ is constructed of a flat plate portion 31 having a height ofsubstantially 10-20 mm and having a flat surface configuration that issubstantially the same as the bottom surface configuration of the secondmain body portion 12′ of the casing 10 and a circular-columnar portion32 projecting downward from the central part of the bottom surface ofthe flat plate portion 31. Between the flat plate portion 31 and thecircular-columnar portion 32 there is interposed a filter 33 consistingof non-woven fabric. Adsorbent 34 is filled in the flat plate portion 31and a hollow fiber membrane module 35 is filled in the circular-columnarportion 32. A large number of raw water inlets 31 a are provided in theentire upper surface of the flat plate portion 31 while, the lower endof the circular-columnar portion 32 is made open and used as a purifiedwater outlet 32 a. Further, a lug portion 31 b is projectingly providedat the center of the surface of the flat plate portion 31.

The casing 10 of the water purifier having attached thereto thepurification cartridge 30 of the above-described construction isdifferent from the former-described construction. The difference is thatan opening 12 e for insertion therethrough of the purificationcartridge, which is used for passing the circular-columnar portion 32 ofthe purification cartridge 30 therethrough, is merely formed in thebottom surface of the second main body portion 12′. However, the otherconstructions of the casing 10 are the same as those of theformer-described embodiment. Therefore, the same symbols are used todenote them and a detailed explanation thereof is omitted.

In the above-described purification cartridge 30, adsorbent is filled inthe flat plate portion 31 having a flat surface configurationsubstantially the same as the bottom surface configuration of the secondmain body portion 12′ constituting the raw water reservoir portion 1 a.Simultaneously, a large number of the raw water inlets 31 a are formedin the surface of the flat plate portion 31. The raw water can therebybe efficiently introduced into the cartridge 30 and contacted with theadsorbent 34. Also, a hollow fiber membrane module 35 is filled in thecircular-columnar portion 32 projecting downward from the flat plateportion 31. And, the water passage rate of this hollow fiber membranemodule 35 is low compared to that of the adsorbent 34. Therefore, theoriginal, or non-processed, water can be allowed to stay in the flatplate portion 31 for a necessary period of time, which enablessufficiently eliminating chlorine or the like by means of adsorbent.

In this embodiment, the projection dimension of the circular-columnarportion 32 is set to be 110 mm to thereby enlarge the total membranearea of the hollow fiber membrane module 35 to thereby further increasethe water passage rate. However, if it is sufficient that the waterpassage rate necessary as a pitcher type water purifier be obtained, thetotal membrane area of the hollow fiber membrane module 35 may be madesmall and the projection dimension of the circular-columnar portion 32may thereby be set to be 50 mm or so. If making small the projectiondimension of the circular-columnar portion 32 in that way, thiscircular-columnar portion 32 becomes unlikely to be immersed within thepurified water that is kept stored in the purified water reservoir 1 b,which is preferable from the standpoint of sanitation as well.

According to a third embodiment of the present invention illustrated inFIG. 7, a pitcher type water purifier 1″ is constructed of a casing 10″and a purification cartridge 40.

The casing 10″ is constructed of a main body portion 14 the upper end ofwhich is open and the lid member 13 that closes the upper end of theopening of the main body portion 14 and at the center of that the lugportion 13 a is formed. The main body portion 14 has formed thereon thehandle 14 a and the pouring opening 14 b integrated therewith, thepouring opening 14 b being closable by the substantially triangular lidpiece 14 c. Further, on the substantially central part of the inner wallsurface over the entire circumferential surface thereof there isprojectingly provided a rib 14 d for attachment of the purificationcartridge.

The purification cartridge 40 consists of a thick plate body that has aflat surface configuration that is substantially the same as the openingconfiguration at the portion, where the rib 14 d is projectinglyprovided, of the main body portion 14 of the casing 10″. Thispurification cartridge 40 is placed on the rib 14 d of the casing 10″.Thereby, the interior of the casing 10″ is partitioned into upper andlower parts by means of the purification cartridge 40. And the upperside of the purification cartridge 40 constitutes the raw waterreservoir portion 1 a while the lower side thereof constitutes thepurified water reservoir 1 b. Incidentally, although no illustration ismade in FIG. 7, it is also possible to tightly fit both of the main body14 and the purification cartridge to each other by adopting a sealstructure wherein an O-ring or gasket is interposed between the both.

The purification cartridge 40 comprises a hollow-cylindrical case member41 whose upper end is closed, and the closed upper end is formed with alug portion 42 and a large number of raw water inlets 43. On the otherhand, the lower end of the case member 41 is as a whole made open toconstitute a purified water outlet 44. At a substantially centralportion of the interior of the purification cartridge 40 there isdisposed a filter 45 consisting of non-woven fabric, whereby theinterior of the case member 41 is partitioned into upper and lowerparts. In the upper half portion of the interior of the case member 41there is filled the adsorbent 46. And, into the lower half portion, ahollow fiber membrane module 47 is fitted in a state where the openingend portion of a hollow fiber membrane 47 b, which has been fixed by apotting material 47 a, is in coincidence with the purified water outlet44.

In the above-described purification cartridge 40, by forming a largenumber of the raw water inlets 43 on the surface of the purificationcartridge 40, it is possible to enlarge the opening area of the rawwater inlets, to increase, at the same time, the number of the openingend portions of the hollow fiber membranes and, therefore, to enhancethe filtering efficiency performed using the hollow fiber membranes. Forthis reason, it is possible to remarkably enhance the processing rate ofthe raw water. Furthermore, this purification cartridge 40 has noportion that projects into the purified water reservoir portion 1 b andthat is immersed in the purified water, which is preferable from thestandpoint of sanitation as well.

FIG. 8 illustrates a fourth embodiment of the present invention.

As illustrated in the figure, a purification cartridge 50 as a wholeconsists of a thick plate body and is dividable into an upper layerportion 51 and a lower layer portion 52. The upper layer portion 51comprises a case member 51 a the upper surface of that is closed, and,in the edge of the open lower end of the case member 51 a, there isformed a threaded groove 51 b that is engagement means with the lowerlayer portion 52. A lug portion 51 c and a large number of the raw waterinlets 51 d are formed with respect to the upper surface portion of thecase member 51 a. The end edge of the open side end is closed by afilter 51 e consisting of non-woven fabric, and, within the upper layerportion 51, there is filled an adsorbent 51 f.

On the other hand, in the lower layer portion 52, at the upper end edgeof the case body 52 a, which consists of a cylindrical body both ends ofwhich are open, there is formed a threaded groove 52 b which isengagement means with the upper layer portion 51. Further, in theinterior of the lower layer portion 52, hollow fiber membranes module 52c is fitted in a state where the end portions of the openings of ahollow fiber membranes 52 f fixed by means of potting material 52 d arein coincidence with the lower end edge of the case member 52 a.

This purification cartridge 50 is formed in the way the upper layerportion 51 filled with the adsorbent 51 f and the lower layer portion 52filled with hollow fiber membranes 52 e are separable from each otherthrough the use of the screw engagement. For this reason, the adsorbent51 f and the hollow fiber membrane 52 f can be independently replacedaccording to their respective service lives, so waste is avoided.

Incidentally, in this embodiment, the upper layer portion 51 and thelower layer portion 52 are fixed through the utilization of the screwengagement. However, a stepped portion for allowing the upper layerportion to be simply placed on the lower layer portion from above may beonly formed. Or, a seal member such as an O-ring, gasket, etc. can beinterposed in between.

1. A pitcher water purifier comprising a casing divided into upper andlower parts, as a raw water reservoir portion and a purified waterreservoir portion, and having a purified water pouring opening incommunication with the purified water reservoir portion and a disposablepurification cartridge placed in communication between the raw waterreservoir portion and the purified water reservoir portion, thepurification cartridge comprising: at least one raw water inlet, atleast one purified water outlet, a single case member having aninterior, and a filter dividing the interior of the single case memberinto an upper part and a lower part, wherein an adsorbent is filled insaid upper part of the interior of the single case member, and is incommunication with the raw water inlet, and hollow fiber membranes, eachhaving a cross-sectional area based on the outer fiber diameter, whichincludes an interior cross-sectional area based on the hollow portion ofthe hollow fiber membrane, are filled in a filling space whosecross-sectional area is constant and communicate with the purified wateroutlet in said lower part of the interior of the single case member,said raw water reservoir portion configured to deliver a very low waterpressure of about 0.0005-0.003 MPa, which corresponds to a water headdifference of between about 5-30 cm in said raw water reservoir portion;a percentage s (%) of a total of the cross-sectional area of the hollowfiber membranes filled in the filling space to the cross-sectional areaof the filling space is 25-58%, the percentage s being defined as:s (%)={(A×F)/S}×100; in which A represents the cross-sectional areabased on the outside diameter of one of the hollow fiber membranes to befilled, F represents the total number of openings that are incommunication with the purified water outlet in said hollow fibermembranes and S represents the cross-sectional area of the space withwhich said hollow fiber membranes are filled in said purificationcartridge; when the purification cartridge is placed in the pitcherwater purifier, the absorbent does not remain in contact with thepurified water; and the upper part filled with the adsorbent isseparable from the lower part filled with the hollow fiber membranesthrough use of a screw engagement.
 2. A pitcher water purifier accordingto claim 1, wherein the casing comprises pressurizing means for applyingpressure to the raw water reservoir portion so as to increase the waterhead difference.
 3. A pitcher water purifier according to claim 2,wherein the pressurizing means comprises a pressurizing pump.
 4. Apitcher water purifier according to claim 1, wherein the purificationcartridge has a columnar configuration, the upper part thereof filledwith the adsorbent has the raw water inlet, and the lower part filledwith the hollow fiber membranes has the purified water outlet.
 5. Apitcher water purifier according to claim 1, wherein the adsorbentcomprises activated carbon in an amount filled of 10-200 g; and a totalmembrane area of the hollow fiber membranes is 0.1-1.0 m².